Summary The Air Canada Airbus A320 (ACA1118) departed Vancouver International Airport, British Columbia, from Runway 08R at 1640 Pacific daylight time. The Vancouver departure north controller cleared the aircraft to turn left to 360 upon reaching 3000feet. At the same time, under the supervision of the same controller, a visual flight rules Cessna 172M was carrying out approved aerial work at 5000feet over the city area, 7 to 10nautical miles east of the airport. The A320 began to turn left shortly after passing 3000feet, and at 1642:52, the pilots received a traffic alert and collision-avoidance system resolution advisory to climb as a result of the Cessna traffic ahead of them. The spacing between the two aircraft decreased to 0.7nautical mile laterally and 700 feet vertically. The A320 pilots saw the Cessna as it was passing on their right; the Cessna pilot did not see the A320. Visual meteorological conditions existed at the time. Although there was no risk of collision because the flight paths were diverging, the safety of the two aircraft had not been assured. Ce rapport est galement disponible en franais. Other Factual Information The Vancouver non-directional beacon (NDB) is 4.1 nautical miles (nm) from the threshold of Runway 26L on the extended centreline of the runway. The NDB is a navigation aid that the controller was using as a reference point for aircraft departing Runway 08R. In the time surrounding this incident, two other visual-flight-rules (VFR) aircraft were engaged in parachute dropping operations in the airspace over the Pitt Meadows airport, about 15nm east of Vancouver, and were operating up to 10000feet. At the time of the incident, the workload for the departure position in the Vancouver terminal was moderate, with normal complexity. About 90 seconds before the incident, there was a controller change-over for the Vancouver departure north position. The controller handover briefing did not mention any proposed air traffic control (ATC) actions for the A320 and the VFR Cessna, because both controllers considered such actions to be the oncoming controller's personal decision. One of the controller's responsibilities was to provide conflict resolution between the instrument-flight-rules A320 and the VFR Cessna. The new departure north controller's plan was to turn the A320 north so as to pass west of the VFR Cessna and avoid the other VFR aircraft operating near Pitt Meadows. Previous experience with other jet aircraft on departure from this runway led the controller to anticipate that the A320 would reach 3000feet approaching the NDB and start the left turn. The controller judged that a turn near the NDB would have provided ample spacing between the A320 and the Cessna. The departure controller's first ATC instruction was at 1641:41 Pacific daylight time1 for ACA1118 to turn to a heading of 360 for traffic when reaching 3000feet. (See Appendix A for a chronology of the events.) The pilot correctly acknowledged this instruction. However, the A320 did not begin to turn north where the controller had anticipated - near the NDB - and the controller recognized a developing traffic conflict. At 1642:16, he instructed the A320 to turn further left to 350, which the pilot acknowledged. About 15seconds after passing 3000 feet, about 2.5nm past the NDB, the A320 began to turn left, to the north. At 1642:30, the controller informed the Cessna pilot about the conflicting A320 traffic. At no time did the Cessna pilot see the approaching A320. The controller saw that the spacing was decreasing and, at 1642:39, directed ACA1118 to turn left to 330 and advised that the Cessna was about 3.5nm ahead at 5000feet. This was the first time that information about the Cessna was provided to ACA1118. The controller did not convey any sense of urgency during this transmission, nor did he incorporate the standard published safety alert phraseology2 to indicate any need for an immediate turn. Almost coincident with the controller's instructions, the ACA1118 pilots received a traffic alert (TA) at 1642:42 from the on-board traffic alert and collision-avoidance system (TCAS) triggered by the VFR Cessna traffic ahead of them. Because of the TA, they did not completely hear the ATC instruction to turn or the information about the Cessna. At 1642:52, the controller repeated his previous transmission, but by this time the pilots had initiated their response to the TCAS resolution advisory (RA) to climb. They did not hear this repeated instruction or traffic information, because it was blocked out by the TCAS warning. At 1643:07, the A320 pilot reported that they had the Cessna in sight, passing below them on their right-hand side. In three subsequent transmissions to ACA1118, the controller advised the A320 pilot that the Cessna pilot had the A320 in sight; in fact, the Cessna pilot never saw the A320. Radar data show that ACA1118 was in a gradual left turn until it passed the Cessna; the aircraft's track was no farther west than 358. ATC information confirms that the A320 had not yet turned to 350. Nav Canada is the principal provider of ATC services in Canada and is responsible for all Canadian civil aeronautical information. Nav Canada is required to monitor all aircraft to ensure conformance with published ATC procedures. The Vancouver International Airport Authority has developed an aeronautical noise management program. Noise-abatement procedures for the take-off climb ensure that the necessary safety of normal flight operations is maintained while exposure to noise on the ground is minimized. According to approved civil aeronautical information documents (Canada Air Pilot [CAP]: Instrument Procedures) in effect at the time of the incident, only two different vertical noise-abatement procedures (VNAP) were authorized at Canadian airports: procedures A and B. These procedures are published under the authority of Nav Canada and were consistent with the two noise-abatement procedures promulgated by the International Civil Aviation Organization (ICAO) and used internationally. In summary, VNAP A provided a steeper climb at slower speed than VNAP B. Recently, ICAO has issued changes to its directives and standards concerning noise-abatement procedures. Nevertheless, one of the basic tenets of noise-abatement procedures in general is that they are not intended to be used solely for air traffic separation. Other procedures, such as standard instrument departures (SIDs), are designed for that purpose. At the time of the incident, all air carriers in Canada were required to follow either VNAPA or VNAP B on take-off from selected Canadian airports. According to the general noise-abatement procedures published in CAP, volume2, all jet aircraft departing from Vancouver were to use VNAPA only and were to follow the assigned SID to 3000feet before proceeding on course. There was a restriction on the SID that aircraft were not to exceed 280knots until above 7000feet above sea level. An important reason for standardizing VNAP A at Vancouver was to provide similar jet aircraft departure performance and to facilitate aircraft turning on course. Nav Canada also believed that using one VNAP procedure at Vancouver would be more useful in managing traffic and reducing performance conflicts between departing jet aircraft. Pilots who fly Air Canada aircraft are instructed to the follow the Air Canada fleet noise-abatement procedures contained in the Transport Canada-approved Air Canada operations manual for the specific aircraft type. The Air Canada fleet procedure differs markedly from VNAP A: the Air Canada vertical profile flown by the A320 aircraft is flatter, and the speed on departure is higher. Accordingly, Air Canada A320 aircraft departing from Vancouver do not follow the published VNAP A profile. Transport Canada inspectors involved in the ongoing oversight of Air Canada were aware of the significant procedural and operational differences that resulted from the implementation across Canada of these unique, fleet-wide noise-abatement procedures. In March 2001, Nav Canada advised Air Canada that Nav Canada had no concerns regarding ATC separation applications with respect to Air Canada's aircraft departing Vancouver operating under [the Air Canada fleet noise-abatement] procedures. Nav Canada advised that it did not anticipate any ATC separation problems at Vancouver or at six other major Canadian airports used by Air Canada. Nav Canada did not examine any operational or performance issues associated with these modified procedures for any of the Air Canada aircraft types at any of the seven airports involved. Nav Canada was unaware of the marked differences between the published VNAP A profile and the Air Canada fleet procedures. The investigation found that Vancouver controllers have determined by experience that when aircraft following VNAP A from Runway 08R cross the Vancouver NDB, they are consistently higher than 3000feet and at approximately 200knots. This was confirmed by a review of the aircraft take-off profiles for the one-hour period surrounding the incident (except for two aircraft whose regular flight paths and altitude profiles were known and expected to differ from the others). Furthermore, Vancouver controllers generally believe that Air Canada aircraft follow VNAP A, since the controllers have not been informed otherwise. Those controllers were unaware that the Air Canada profile differed procedurally from the approved VNAPA. Anecdotal information suggested that few Vancouver controllers had encountered significant separation difficulties with departing Air Canada aircraft. Flight profile tests carried out in an A320 simulator after the incident show that an A320, configured the same as the incident aircraft and in controlled conditions, crosses the NDB at about 3650feet and 205knots when following VNAPA; when following the Air Canada VNAP, the aircraft crosses the NDB at about 3050feet and 230knots. In this incident, the A320 crossed the NDB at 2600feet and 230knots and passed 3000feet at 250knots. The A320 had accelerated to 280knots by the time of the TCAS RA. The take-off weight of the A320 was 69200kg; the maximum take-off weight for this aircraft was 75500kg. The pilot flying was controlling the A320 manually. Reportedly for passenger comfort, he chose a flatter flight path and a higher climbout speed than the parameters indicated on the Air Canada VNAP. The pilot also turned the aircraft using 15 of bank when 25 would have been normal. Appendix B briefly demonstrates the general relationship between airspeed and radius of turn for 15 and 25 of bank and the time to complete a 90 turn at 15 of bank. For example, a 50-knot increase in speed from 230 to 280knots requires about a 50% greater radius of turn, and the radius of turn at 15 of bank and 280knots (25900feet) is about 2 times the radius that the controller would have expected (10000feet). The pilot assessed that, since the controller's initial instruction to turn to 360 was based on his reaching a specified altitude, there was no pressing need to turn his aircraft as a result of the advised traffic. As well, he concluded that, since the controller had issued a turn to the left, the traffic conflict was ahead and/or to his right. It was not until 15seconds after the A320 had begun its left turn - that is, 44seconds after passing the NDB - that the controller transmitted to the crew information about the conflicting traffic to the north of their position. The receipt of this information by the pilots, however, was thwarted twice by the TCAS warnings and activities on the flight deck.